1. Chapter 5: Investigate! Lists, Arrays, and Web Browsers

2. Objectives  Create an Android project using a list  Develop a user interface that uses ListView  Extend the ListActivity class  Use an array to create a list  Code a setListAdapter to display an array  Design a custom ListView layout with XML code  Display an image with the ListView control  Change the default title bar text

3. Objectives  Code a custom setListAdapter for a custom layout  Call the onListItemClick method when a list item is selected  Write code using the Switch decision structure  Call an intent to work with an outside app  Open an Android Web browser  Launch a Web site through the use of a URI using an  Android browser  Test an application with multiple decisions

4. Creating a List  Lists are one of the most common designs in mobile apps – Scrollable – Selectable – Programmable to bring up the next Activity (screen)

5. Creating a List Steps to complete the app:  Create a list using a ListView control.  Define an array to establish the items of the list.  Add the images used in the project.  Define an XML file to design the custom list with a leading image.  Code a switch decision structure to handle the selection of items.  Open an Android Web browser to display a specified Uniform Resource Identifier (URI).  Create multiple classes and XML layout files to display pictures of attractions.

6. Creating a List  Opening screen contains a vertical list of attractions  List is automatically scrollable if it exceeds the window size  ListView is better than TableLayout View because each row can be selected for further action  Selecting an item opens up a related Web page or an image of the attraction

7. Creating a List Extending a ListActivity  A ListActivity class is needed to display a list of items  An ExpandedlistView can be used to provide a two-level list

8. Creating a List  Creating an Array Array variables can store more than one value  Different from other data types that can hold only one value  Each individual item in an array is called an element  Refer to each element using an index in the array

9. Creating a List  Declaring an Array Square brackets [ ] are used to define an array  Curley braces { } contain the list of items in the array  String[] attraction={"Alcatraz Island", "Ferry Marketplace", "Golden Gate Bridge", "Cable Car Trolley", "Fisherman's Wharf"};

10. Creating a List  Using a setListAdapter and Array Adapter An adapter provides a model for the layout and converts the data into a list  The setListAdapter connects the list items to the images or Web pages they represent  An array adapter supplies the array data to the ListView setListAdapter(new ArrayAdapter (this,android.R.layout.simple_list_item_1, attraction));

11. Creating a List Adding the Images to the Resources Folder  Images must be located in the drawable-hdpi folder  Remember that images may be subject to copyright laws

12. Creating a List Creating a Custom XML Layout for ListView

13. Creating a List Creating a Custom XML Layout for ListView

14. Creating a List Changing the Title Bar Text  Custom titles can appear in the title bar at the top of the window

15. Creating a List Coding a setListAdapter with a Custom XML Layout Built-in layout is called simple_list_item_1

16. Creating a List  Using the onListItemClick method onListItemClick() is called when an item from the list is selected  The item’s position in the list is captured so the app knows which of the items was selected  The position represents the number of the item in the list

17. Creating a List Decision Structure – Switch Statement  If statements are also decision structures  The switch statement is used when there are many list items to be evaluated  Can only evaluate integers or single characters  The keyword case is used to test each item  The keyword break is used to exit the switch decision structure

18. Creating a List Android Intents Android intents send and receive activities and services including: Opening a Web page  Calling a phone number  Locating a GPS position on a map  Posting notes to a note-taking program  Sending a photo  Posting to a social network

19. Creating a List Launching the Browser from an Android Device The intent sends the browser a URI (Uniform Resource Identifier)  URI is similar to URL (Uniform Resource Locator)  URI has additional information necessary for gaining access to the resources required for posting the page  The action called ACTION_VIEW (must be in CAPS) is what actually displays the page in the browser  ACTION_VIEW is the most common action performed on data

20. Creating a List Designing XML Layout Files  XML layout files must be designed to display an ImageView control with an image source file

21. Creating a List

22. Adding Multiple Class Files  A new class is needed to display each image  Classes must be referenced in the Android Manifest File  Code for Wharf.java class (Bridge and trolley already created)

23. Creating a List  Opening the Class Files startActivity opens the next Activity which launches the appropriate X  Running and testing the Application Be sure to test every option Should handle all clicks

24. Summary  The Java View class creates a list and makes it scrollable; use a ListView control to select each row for further action  Extend the ListActivity class in Main.java to display a ListView control  Declare list items in an array variable  The index provides access to each element in the list (the list begins with 0)  To declare an array, specify the data type followed by the values

25. Summary  Use an adapter to display the values in the array  A ListView control is a container for the list items and the adapter binds the elements of the array to the ListView layout statements if the condition is false  Drag controls from the palette to the emulator for a simple design  Add code to the main.xml file to get a custom layout

26. Summary  App names are displayed in the app title bar – can be customized  setListAdapter has 3 parameters:  this class  The layout used to display the list  The array containing the list values  Code the onListItemClick method to respond to the event of the user’s selection  Use the switch decision structure with a list or menu

27. Summary  Android intents send and receive activities and services  Test every possible combination of clicks, including incorrect user entries before publishing the app